Aqualung Legend LX O-ring Shore A Hardness / Duro

[Peter Vegas]

Hello,
I'm trying to find out o-ring Shore A / Duro hardness for Aqualung Legend LX (present) model as I'm not able to purchase it from any dealer.
The o-ring is a standard overhaul part 820009P as seen in the image below (Item 28).
This o-ring shows up in older (2011) service manual as 473056 O-ring 1.78x5.28 EPDM 80ShA.
Can anyone confirm that the current 820009P o-ring is also EPDM with hardness of 80 Shore A?
Thank you.

 

[Zef]

The HP port (part # 46 in the diagram) should take a 90 shore o-ring.
The MP port (part # 44) should take a 70 shore o-ring.
I am pretty sure that part # 28 should be a 90 shore o-ring as it receives high pressure at the cylinder valve - 1st stage ACD interface.

80 shore is a happy medium between 70 and 90...70 is typically used for LP/MP applications and 90 is typically used for HP applications to prevent the o-ring extruding out of position under the high pressure.

-Z

 

[Peter Vegas]

Hey Z. Thank you for your response. Looks like Part # 24, is also used with ACD (yoke) and filter. This area would also be under high pressure. Therefore requiring 90 shore also. Would you agree?

 

[Zef]

Hey Z. Thank you for your response. Looks like Part # 24, is also used with ACD (yoke) and filter. This area would also be under high pressure. Therefore requiring 90 shore also. Would you agree?

Short answer: Yes, I agree.

Long Answer:
You can use 90 shore every where o-ring part #24 is specified in the diagram...you dont need a to use a 70 shore o-ring on the mp port plug unless you really want to have 2 versions of the same o-ring....the mp port plug does not need 90 shore, per se, but it won't be a problem there either. Where a harder o-ring could be problematic is in an application wherethe o-ring moves and a softer o-ring is specifically specified...this is called a dynamic application....because the mp port o-ring is static once the port plug is installed and the o-ring is captive, there should be no problem with the harder composition.

-Z